understanding
prediction
communication
You are doing this all the time - there are many reasons to make this process explicit (computer aided modeling)
Clearly define your goal (a question you want to answer, hypothesis you want to test, prediction you want to make) - as precisely as possible
Design or Select your model
Implement the model
Evaluate the model and quantify uncertainty
Apply the model to the goal
Communicate model results
What are your inputs-outputs?
What’s in the box (the model itself) that gives you a relationship between outputs and inputs?
Inputs: Varying; think x of a x vs y regression
Parameters: single values that influence relationships in the model
Transfer Function (model): Equations that transfer inputs to outputs given parameters
Outputs: what you want to estimate
What are the processes/relationships that you think are important to translate inputs to output
Transfer function (mathematical representation)
Parameters, values that influences how the model relationships work
There are often multiple “boxes” internal to a model
Often more complicated than a simple regression…
So we need to think through what the relationships are; the processes are that we want to take in to account
Conceptual models are a good place to start
Precipitation = Evapotranspiration + Change in Storage
P = ET + ΔS
(at global scales ΔS includes streamflow since that water is still “stored” in the earth
Goal - estimate streamflow fromm multiple source (surface and subsurface)
More complex model couple sub-models
How do ecological and human factors interact to influence fire regimes
[source](https://www.boundless.com/biology/textbooks/boundless-biology-textbook/ecosystems-46/energy-flow-through-ecosystems-257/productivity-within-trophic-levels-952-12212/](https://www.boundless.com/biology/textbooks/boundless-biology-textbook/ecosystems-46/energy-flow-through-ecosystems-257/productivity-within-trophic-levels-952-12212/)
Serrano-Cinca C, Gutiérrez-Nieto B, Reyes NM, A Social and Environmental Approach to Microfinance Credit Scoring, Journal of Cleaner Production (2015), doi: 10.101
[Available from] (https://www.researchgate.net/publication/282855291_A_Social_and_Environmental_Approach_to_Microfinance_Credit_Scoring).
Figure 1. Flowchart of the social and environmental microcredit scoring decision process. The model includes financial assessment and social impact assessment.
Fig. 2. Flow-chart illustrating the working steps of glacial lake detection based on the normalized difference water index (NDWI), lake-outburst probability assessment and lake classi fi cation in the Indian Himalayas.
Rouce et al., Hydrol. Earth Syst. Sci., 20, 3455–3475, 2016 www.hydrol-earth-syst-sci.net/20/3455/2016/ doi:10.5194/hess-20-3455-2016
There are many different ways to classify models
A useful classification looks at how models deal with space, time, and process
Useful because the type of model will have implications for how you build and use/run the model
Stochastic: Model output is the probability of flood events of a magnitude greater than 500 m3/sec given rainfall probability distribution (artificial or generated from data) for a 100km2 watershed Deterministic: Model output is the depth of flood given a rainfall event of 10cm over a 100km2 watershed
Lumped - single point in space, or space doesn’t matter
Spatially distributed - model is applied to different “patches” in space spatial units are independent
spatial units interact with each other
Static - Processes or Variables modeled do not evolve with time
Dynamic - model elements evolve through time - and variables/results at one time step typically depends on previous time step
Abstract - relationship between inputs and output depends on parameters that don’t necessarily have a physical meaning
Physically based - parameters do have a physical meaning (could be measured) - relationships derived from first principles (theory) of how things work
serc.carlton.edu Abstract
Physically based
Abstract Physically based http://ks.water.usgs.gov/pubs/reports/paclim99.html
Pictorial representation of how you think about your system, and what needs to be included in the model to answer your questions (or achieve your modelling goal)
There are many software tools available for generating conceptual models, I like
[Diagrams.net]{https://www.diagrams.net/}
Some model designers uses standard symbols for the different model components
Building Models
Conceptual Models
For assignment one you will create a conceptual model to be presented in class. You will work in groups of 3-4.
Identify an environmental problem that would benefit from a model. Summarize the goal of the model in a few sentence. Draw a conceptual model, consider - inputs, outputs, important processes/mechanisms/interactions, reservoirs/stores, other intermediate variables or steps, relationships between variables. Put your conceptual model on a single slide and be prepared to present the key inputs and outputs of the model, and the purpose of the model in class
Also add the slide on Gauchospace
Conceptual model that will be built upon:
This will be a conceptual model of almond yield anomaly. Review the Lobell et al. 2006 paper; specifically look at the equation for almonds in table 2. Draw a conceptual model to represent this equation. Be sure to include all that apply: inputs, outputs. Identify the output (as precisely as you can) on the conceptual model. Be sure to understand what anomaly means! We will go over this together in class. Submit this model as a figure.
Submit the following to gauchospace
the one paragraph description of your model
the slide with your conceptual model for your selected model
slide/figure of the almond conceptual model
Submit as a group